Death during pregnancy or childbirth would have been common in the ancient world, but these stories are often invisible in the archaeological record. However, in a new study of ancient DNA, researchers reported evidence of a woman who died of a pregnancy complication — specifically, a fatal bacterial infection — 800 years ago at Troy.

The woman was about 30 years old when she died, in the 13th century A.D. She was buried in a stone-lined grave at a Byzantine-era farming community's cemetery in Troy, the ancient city located in what is now northwest Turkey, immortalized by Homer in the "Iliad."

Archaeologists from Germany's University of Tübingen have been working at Troy since the 1980s, and in 2005, they excavated this woman's remains. The woman's skeleton was notable for having two strawberry-size nodules sticking out just below the ribs. Initially, the researchers thought these calcified lumps were the result of tuberculosis, or perhaps urinary or kidney stones, the scientists said. The team said it came up with a different diagnosis after cracking open the nodules. [27 Devastating Infectious Diseases]

Inside these little stones, the researchers saw well-preserved microfossils resembling Staphylococcus, the bacteria that causes staph infections. For confirmation, the scientists sent the nodules to the lab of Hendrik Poinar, an expert in ancient DNA at McMaster University in Canada.

Poinar's lab took DNA samples from the nodules and found genetic material from human cells (of both the woman and possibly her male fetus), as well asbacterial cells. One would expect to find this type of combination in anabscess, the researchers wrote in their study, published yesterday (Jan. 10) in the journal eLife.

"Amazingly, these samples yielded enough DNA to fully reconstruct the genomes of two species of bacteria, Staphylococcus saprophyticus and Gardnerella vaginalis, which infected the woman and likely led to her death," Poinar said in a statement.

"There are no records for this anywhere," he added. "We have almost no evidence from the archeological record of what maternal health and death was like until now."

The strain of G. vaginalisactually looked similar to strains of the bacteria that still cause an infection known as bacterial vaginosis in women today, the scientists said. However, the strain of staph bacteria that infected the woman from Troy looks more like a strain that now infects livestock, not humans, the researchers said.

"The Troy isolate is in this really interesting position between the cow- and human-associated staph," study author Caitlin Pepperell, a professor of medicine and medical microbiology at the University of Wisconsin-Madison, said in the statement. "It looks like the bug that caused her disease was in a different niche than what we see associated with human infections today. … We speculate that human infections in the ancient world were acquired from a pool of bacteria that moved readily between humans, livestock and the environment."